I. Field
The present disclosure relates generally to communication, and more specifically to techniques for estimating thermal noise and rise-over-thermal (RoT) in a wireless communication system.
II. Background
Wireless communication systems are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These systems may be multiple-access systems capable of supporting multiple users by sharing the available system resources. Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal FDMA (OFDMA) systems, and Single-Carrier FDMA (SC-FDMA) systems.
In a CDMA communication system, multiple user equipments (UEs) may currently transmit on the uplink to a Node B. The transmission from each UE acts as interference to the transmissions from other UEs at the Node B. The received signal quality of a given UE is dependent on various factors such as the amount of transmit power used by the UE, the path loss from the UE to the Node B, the amount of interference observed by the UE at the Node B, etc. The total interference at the Node B increases when the UEs increase their transmit power and/or when more UEs are added. At some point, the UEs cannot further increase their transmit power and no more UEs can be added. The capacity of the CDMA system may thus be interference-limited on the uplink.
RoT is a ratio of total noise and interference to thermal noise at a Node B. RoT is a fundamental measure of loading on the uplink in a CDMA system. It may be desirable to accurately estimate RoT in order to maintain the uplink loading below a target level to avoid system instability. An accurate estimate of thermal noise is needed for an accurate estimate of RoT.